Resistant
hypertension is defined as blood pressure that remains uncontrolled in spite of >or= 3
antihypertensive medications at effective doses, ideally including a
diuretic. Although exact prevalence is unknown, clinical trials suggest that 20% to 30% of study participants are resistant.
Hyperaldosteronism,
obesity, refractory volume expansion, and
obstructive sleep apnea are common findings in resistant
hypertension patients. Multiple studies indicate that primary
aldosteronism (PA) is common (approximately 20%) in patients with resistant
hypertension. Screening for PA is recommended for most patients with resistant
hypertension, ideally by measurement of 24-hour urinary
aldosterone excretion, or by the plasma
aldosterone/plasma
renin activity ratio. Successful treatment of resistant
hypertension is predicated on improvement of lifestyle factors; accurate diagnosis and treatment of secondary causes of
hypertension; and use of effective multidrug regimens. A long-acting
diuretic, specifically
chlorthalidone, is recommended as part of the treatment regimen. Recent studies demonstrate that
mineralocorticoid receptor antagonists provide substantial
antihypertensive benefit when added to multidrug regimens, even in patients without demonstrable
aldosterone excess.